The Lightning Field (1977), by the American sculptor Walter De Maria, is a work of Land Art situated in a remote area of the high desert of western New Mexico. It is comprised of 400 polished stainless steel poles installed in a grid array measuring one mile by one kilometer. The poles -- two inches in diameter and averaging 20 feet and 7½ inches in height -- are spaced 220 feet apart and have solid pointed tips that define a horizontal plane. A sculpture to be walked in as well as viewed, The Lightning Field is intended to be experienced over an extended period of time. A full experience of The Lightning Field does not depend upon the occurrence of lightning, and visitors are encouraged to spend as much time as possible in the field, especially during sunset and sunrise. In order to provide this opportunity, Dia offers overnight visits during the months of May through October.